Hydroformylation is a commercially important technology in the chemical industry. Aldehydes are prepared via the hydroformylation or OXO reaction, according to which one mol of unsaturated compound is reacted with synthesis gas (syngas) having a molar ratio of hydrogen to carbon monoxide of 1:1 as shown below:RHC═CH2+H2+CO→RH2C—CH2—CHOwherein R is an organic radical. Because of the high chemical reactivity of aldehydes, further chemical derivatives such as alcohols, carboxylic acids, etc. can readily be prepared in large volumes which, in turn, can be further converted into, for example, ester compounds.
Using synthesis gas as the raw material for the OXO reaction requires the adjustment of the molar ratio of the hydrogen to carbon monoxide to levels near 1:1 in many processes and excess of hydrogen has to be removed. In some cases, hydrogen can be used downstream in hydrogenation processes, such as in the manufacture of alcohols or it can be sent to a logistic system for use by further consumers. However, there is a need to decrease the hydrogen to carbon monoxide ratio in order to reduce and/or eliminate excess hydrogen because of the operating and capital expense of removal and redirecting these by-product streams.
The inventive method and apparatus may also be used to process hydrocarbon and other byproduct streams not related to the OXO process, that is oils, alcohols, olefins and other liquids having from 3 to 15 carbon atoms.
In general the liquid waste oils from OXO processes comprise olefinically unsaturated hydrocarbons, longer chain hydrocarbons and oxygenated hydrocarbons. Currently, these liquid waste oils, which generally do not contain any phosphine (PR3) and/or sulfur, are sent to boilers to be incinerated and attempts are made to recover the heat value of these liquid waste oil streams. Heat recovery, while somewhat beneficial, wastes the raw material potential of the oils and requires boiler capacity which is expensive and better utilized on less useful by-products in a chemical plant. Thus, there is a need to more effectively utilize liquid waste oils from an OXO process as well.
Recovered byproduct material may contain a significant amount of non-volatile components which should be removed prior to recycling the material into the production system since these components can cause excessive wear or produce deposits requiring shut-down and cleaning.
In the prior art, the above described deficiencies have not been addressed, despite the availability of numerous technologies to make synthesis gas.
U.S. Pat. No. 3,980,591 discloses a process for recovering particulate carbon using an extractant derived from oxo byproducts, forming a dispersion and using the dispersion as synthesis gas feed.
British Patent Specification 1 568 342 discloses an apparatus for the manufacture of synthesis gas in which a liquid fuel oil and natural gas are mixed and then fed to a vaporizer with a controlled outlet temperature to provide a certain proportion of vapor and liquid. This mixture is then sent to a separator, in which impurities present in the liquid fuel oil are removed as a bottom fraction while a purified vapor fraction goes to the reformer section (page 4, left/right column, bridging lines 48-80, FIG. 1).
WO 2009/065559 discloses a process for producing synthesis gas and hydrogen from liquid hydrocarbon feed stocks generated during refining processes. The recovered hydrocarbon stream is mixed with an oxidizing stream and optionally with a gaseous hydrocarbon stream and then sent to an oxidizing zone wherein a catalytic partial oxidation occurs. Likewise, WO 2009/008092 discloses a process for the production of synthesis gas in the process of the manufacturing of kerosene and gas from natural gas, wherein light hydrocarbons separated by distillation are recycled and treated with steam to produce synthesis gas.
EP 2 103 567 A1 refers to the production of synthesis gas with steam from oxygenated hydrocarbons like glycerol together with natural gas. In this reference, there is described a first step wherein a vapor phase mixture comprising steam and an oxygenated hydrocarbon with a molar ratio of H2O:C of at least 2 is prepared. Preferably, said mixture is further mixed with natural gas prior to its catalytic conversion into synthesis gas. Further, the oxygenated hydrocarbon is present as droplets of a certain size. The droplets are generated with an atomizing nozzle, which is aided by steam. Generally speaking, introduction of steam increases the hydrogen content of the syngas produced which is undesirable in an OXO process where reduced levels of hydrogen are typically required. Excess hydrogen needs to be removed which adds expense and complexity to the OXO production process as will become apparent from the discussion which follows.
Other references of interest are U.S. Pat. Nos. 7,670,586 and 7,214,720 which include description of synthesis gas preparation.